1. Field of the Invention
The invention relates to a headrest control apparatus and a method for controlling an active headrest, which protect the occupant by moving the headrest forward prior to a collision with a following vehicle.
2. Description of the Related Art
A rear collision occupant protection apparatus is known which, when predicting a collision with a following vehicle, detects the position of the occupant's head using a senor in the headrest and moves the headrest forward to a position near the occupant's head (For example, refer to U.S. Pat. No. 5,694,320).
Such control for protruding the headrest (moving the headrest forward) is normally executed prior to the occurrence of a collision between the subject vehicle and a following vehicle after the same collision has been predicted to occur unavoidably. When such a predicted collision has been avoided or when the headrest has been moved unnecessarily, the headrest that has been moved forward interferes with the driver. However, none of the conventional headrest control apparatuses addresses the issue on when the headrest that has been moved forward needs to be returned to its initial position (moved back to its retracted position).
Further, in a state where two or more collisions may be predicted consecutively, it may be the case that a collision with a following vehicle is predicted immediately after a collision with other following vehicle, which was predicted previously, has been avoided. In such a case, if the occupant protection apparatus is adapted to move the headrest back from the forward position to the initial position at a fixed timing, the headrest may be held in the forward position for only a short period of time during the second predicted collision or the headrest may fail to be moved to near the occupant's head prior to the second predicted collision, resulting in an insufficient use of the occupant protection function (the function for reducing whiplash injuries) of the occupant protection apparatus.